Rat cellular retinol-binding protein II: Use of a cloned cDNA to define its primary structure, tissue-specific expression, and developmental regulation

E. Li, L. A. Demmer, D. A. Sweetser, D. E. Ong, J. I. Gordon

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

The primary structure of rat cellular retinol-binding protein (CRBP) II has been determined from a cloned cDNA. Alignment of this 134-amino acid, 15,580-Da polypeptide with rat CRBP revealed that 75 of 133 comparable residues are identical. Both proteins contain four tryptophan residues, which occupy identical relative positions in the two primary structures, providing a structural explanation for their similar fluorescence spectra when complexed to retinol. Two of the three cysteines in each single-chain protein are comparably positioned. Both polypeptides contain reactive thiol groups, but the rate of disruption of CRBP II-retinol complexes by p-chloromercuribenzoate is greater than that of CRBP-retinol. The small intestine contains the highest concentrations of CRBP II mRNA in adult rats. CRBP II mRNA is first detectable in intestinal RNA during the 19th day of gestation, a time that corresponds to the appearance of an absorptive columnar epithelium. Unlike in intestine, a dramatic fall in liver CRBP II mRNA concentration occurs immediately after birth. The CRBP II gene remains quiescent in the liver during subsequent postnatal development. These data suggest that ligand-protein interactions may be somewhat different for the two rat CRBPs. They also support the concept that CRBP II plays a role in the intestinal absorption or esterification of retinol and suggest that changes in hepatic metabolism of vitamin A occur during development.

Original languageEnglish
Pages (from-to)5779-5783
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume83
Issue number16
DOIs
StatePublished - 1986

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